The invention relates to the field of amplifiers, and in particular to differential amplifiers removing output distortions.
Differential amplifiers are commonly employed as key components in many integrated circuits. However, the usefulness of differential amplifiers in many instrumentation type applications is often limited by non-linearities in their gain characteristics. These non-linearities also limit the dynamic range of input signal voltage magnitudes over which the amplifiers can be employed.
The linear dynamic range of a differential amplifier can be extended through the use of “emitter-degeneration”. In accordance with this approach, the amplifier is provided with a pair of constant-current sources separately connected to the emitters of the transistors of the amplifier and further an “emitter feedback” resistor is connected between the emitters of these transistors. This type of circuitry reduces non-linearities in the gain of a differential amplifier but only to a limited extent.